1. Field of the Invention
This invention relates to an image sensing apparatus which senses an image of an object to be photographed and is arranged to form and produce a color image signal corresponding to the image of the object.
2. Description of the Related Art
There has been known a technique for automatically adjusting the white balance of an image sensing apparatus such as color video camera on the basis of the signal output of an image sensor. The automatic white balance adjustment is accomplished, for example, by automatically controlling amplification factors for R and B signals produced by the image sensor in such a way as to bring closer to a given reference value the integration values of color-difference signals obtained by converting R, G and B signals produced by the image sensor.
However, in a case where a major part of the image sensing plane of the color video camera is occupied by the color of some object such as the image of a colored object or an object in front of a colored wall obtained in close-up shooting with the color video camera, the adoption of the above stated automatic white balance adjustment method results in white balance adjustment to an unnatural color. For example, if the white balance adjustment deviates toward green or cyan, the color thus obtained is greatly disagreeable to the human eye in terms of visual sensation. It has been, therefore, considered very important for the automatic white balance adjustment to solve this problem.